Medical research and practice produce a large amount of information which must be displayed and recorded as a sequence of pictures; these derive typically, for example, from fluoroscopy, nuclear medicine, two-dimensional ultrasonic examination, and activity monitoring. For many such applications closed circuit television has provided an excellent approach to displaying sequences of pictures. However, physiological data, such as EKG, blood pressure, blood flow or respiration representing signals are often concurrently available but have heretofore not been easily displayed on video monitors
It is known to display signals representing physiological data on cathode ray oscilloscopes. A prior art system for displaying electrocardiographic (EKG) signals on a cathoderay oscilliscope is described in U.S. Pat. No. 3,853,119 to Peterson et al., issued Dec. 10, 1974. An analog EKG signal is digitalized, stored in a memory for a predetermined period of time and then reconverted back into analog EKG signal for application to the vertical deflection inputs of the oscilliscope. The delay of the signal using the digital electronic circuitry provides requisite flexibility so that it may be utilized to display real time EKG signals or high speed EKG signals which have been collected and are being played back. The system disclosed in the fore-mentioned patent to Peterson et al. does not provide for the simultaneous viewing by a therapist, investigator or diagnostician of a fluoroscopic or ultrasonic image of the heart of the patient from whom the electrocardiographic signals are derived, a distinct disadvantage.
A prior art system employing video equipment for monitoring of body function activities has been described in the U.S. Pat. No. 3,613,669 to Corbin et al., issued Oct. 19, 1971. In this known system a plurality of body function activities such as cardiac conditions are monitored from a remote station. Electrical signal representations of each activity, produced by conventional sensors and/or pairs of leads, are stored temporarily in a storage oscilliscope. A visual display of the electrical signal representations appears on the face of the oscilliscope. A vidicon TV camera scans the visual display of such signals, its output video signals being distributed to a number of remote viewing stations. At each viewing station, the video signals are fed to a conventional TV monitor. No provision is made for viewing simultaneously an image of an ongoing physiological activity, such as a fluoroscopic or ultrasonic image of a patient's beating heart.
It has been proposed to modify systems for remote monitoring of body function activities of the type disclosed in the fore-mentioned patent to Corbin et al. by providing an additional vidicon TV camera and operatively arranging it to scan an image of an ongoing physiological activity, such as an image of a beating heart produced on the screen of a fluoroscope or the like. The outputs from the two vidicon TV cameras are combined in a conventional video mixer and thereafter fed to a common TV monitor. While the physiological data and physiological activity image can be viewed on a single TV monitor, several disadvantages and shortcomings remain. The thus expanded system requires two TV camers, two intermediate visual display means, one of them being a rather complex storage oscilliscope. The thus modified system is complex, expensive and unwieldly.